Apparatus for the production of elongated conical metallic articles

ABSTRACT

Conical metallic blanks for the production of progressive helical springs are produced by rotating an elongated metallic rod about its axis, by simultaneously moving a die said die having three equidistant idler rolls each with an axis arranged askew relative to said die axis and by moving the rolls toward the axis of the workpiece in accordance with a predetermined pattern so that the rolls convert the workpiece into a blank which tapers from one end toward the other end, either gradually or stepwise. The means for moving the rolls toward the axis of the workpiece comprises a fixed template and a scanning arm whose follower tracks the template and which transmits motion to the rolls by way of a turnable ring and pivotable one-armed levers.

Waited States Patent [191 [111 3,810,375 Uehm May 14, 1974 [54] APPARATUS FOR THE PRODUCTION OF 2,330,81 1 10/1943 Darner et al 72/81 ELONGATED CQNICAL METALLIC 2,385,498 9/1945 Clifford ARTHCLES 3,363,442 1/1968 Kennedy et al 72/78 [75] lnventor: Otto Oehm, Werdohl, Germany FOREIGN PATENTS OR APPLICATIONS 1,204,814 9/1970 Great Britain 72/100 [73] Assignee: Stahlwerke Bruninghaus Gesenschafl Beschrankter Primary Examiner-Lowell A. Larson Hammg westhofen/westfalen, Attorney, Agent, or Firm-Michael S. Striker Germany I [22] Filed: Sept. 21, 1972 [57] ABSTRACT [21] Appl 290,836 Conical metallic blanks for the production of progressive helical springs are produced by rotating an elon- Relmed Applicatifin Data gated metallic rod about its axis, by simultaneously [62] Division of Ser'. No. 826,943, May 22, 1969, Pat. No. moving a die said die having three equidistant idler 3,693,390- rolls each with an axis arranged askew relative to said die axis and by moving the rolls toward the axis of the Ffll'eigll Application Priority Data workpiece in accordance with a predetermined pat- Nov. 4, 1967 Germany 27537 tern so that the rolls convert the workpiece into a blank which tapers from one end toward the other [52] US. Cl. ..72/81, 72/84 end, either gradually or stepwise. The means for mov- [51] Int. Cl B21b 31/22 ing the rolls toward the axis of the workpiece com- [58] Field of Search 72/78, 81, 84, 100 prises a fixed template and a scanning arm whose follower tracks the template and which transmits motion [56] References Cited to the rolls by way of a turnable ring and pivotable UNITED STATES PATENTS 6/1854 Pratt..., 72/100 one-armed levers. I

14 Claims, 3 Drawing Figures l APPARATUS FORTHE PRODUCTION OF ELONGATED CONICAL METALLIC ARTICLES CROSS-REFERENCE TO RELATE APPLICATIONS The present application is a divisional application of the copending application Ser. No. 826,943 filed May 22, 1969 and now U.S. Pat. No. 3,693,390.

BACKGROUND OF THE INVENTION The present invention relates to an apparatus for the production of elongated metallic articles, particularly for the production of blanks which can be utilized in the manufacture of so-called progressive helical springs. Still more particularly, the invention relatesto an apparatus for conversion of elongated metallic. rods of constant diameter into elongated blanks which taper from one end toward the other end.

Recent types of automotive vehicles often employ progressive helical springs, i.e., springs wherein the diameter decreases from one end toward the other end. At the present time, such springs areobtained by coilin g of metallic blanks which taper from one end toward the other end, and the blanks are customarily produced by turning of metallic rods with templates, milling, grinding and/or hammering. Such methods of producing tapered blanks are quite expensive, especially since the rods must be machined with a high degree of precision and the blanks must have a very satisfactory surface finish. Furthermore, when the blanks are produced by a material removing method, such as milling or turning, the losses in valuable material (usually highquality spring steel) are considerable.

SUMMARY OF THE INVENTION An object of the present invention is to provide a l novel and improved apparatus for converting elongated rod-shaped metallic workpieces into blanks, which from different types of metallic workpieces and of producing different types of blanks from identical or different workpieces.

Still another object of the invention is to provide a novel die for use in the above outlined apparatus.

One feature of my invention residesin the provision of an apparatus for converting rod-shaped elongated metallic workpieces of at least substantially constant diameter into blanks each of which tapers in a direction from one end towardthe other end. The apparatus comprises means for subjecting a workpiece to what can be termed a drawing'or stretch-rolling action, and intensifying the drawing action in a direction from the one toward the other end of the workpiece. In accordance witha presently preferred embodiment, the apparatus comprises means for rotating the workpiece about its axis in the course of the drawing or stretchrolling action. The latter can be carried out in two or more successive stages.

If the intensifying is gradual, the diameter of the resulting blank decreases gradually (i.e., constantly) in a direction from one end toward the other end of the blank. If the intensifying includes effecting gradual reduction of at least two axially spaced sections of the workpiece and effecting a steeper reduction in the di- BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary transverse sectional view of an apparatus which embodies one form of the invention, substantially as seen in the direction of arrows from the line l-l of FIG. 2, with the workpiece omitted;

broken away; and

FIG. 3 is a sectional view substantially as seen in the direction of arrows from the line IIIIII of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing in detail, there is shown an apparatus which can convert elongated metallic rodshaped workpieces 1 into blanks or semifinished products which taper from one end toward the other end. The apparatus comprises a die 3 which includes three or more preferably equidistant drawing members in the form of rolls 2 eachof which has a convexly curved surface in section comprising three different parts and is rotatable about its own axis. The rolls 2 define a passage 23 for the workpiece l and are movable toward and away from the axis of the die 3; such axis is normal to the plane of FIG. 1 and coincides with the axis of the workpiece l, as viewed in FIG. 2. The ends of the workpiece 1 are held by and clamped in supporting means which includes two supporting members 20 (one shown in FIG. 2). These supporting members 20 can constitute the headstock and the tailstock of a lathe and are rotatable about the axis of the workpiece 1 whereby the I latter shares suchrotary movement. One of the supporting members 20 is preferably movable in the axial direction of the workpiece to compensate for elongation or draft which takes place during treatment. At least one .of the supporting members 20 is fixedly mounted in the frame of the lathe to hold the corresponding end portion of the workpiece 1 against axial movement during conversion into a tapered blank. The supporting means for the die 3 comprises a carriage 21 which is mounted on suitable ways (not shown) of the lathe in such a way that the axis of the die 3 coincides with the axis of the properly held'workpiece 1. The drive means for moving the carriage 21 in the direction of the axis of the workpiece l (i.e., in axial direction of the die 3) comprises a cable 22 which is coupled to the carriage and can move it in-a direction to the left, as

FIG. 2 is a plan view of .the structure shown in FIG. 1, with a portion of the supporting means for the die viewed in FIG. 2. A second drive means is provided to rotate the workpiece 1 about its axis; such drive means includes a gear or pulley 24 (indicated in FIG. 2 by phantom lines) which can rotate the workpiece l with or relative to the adjoining supporting member 20.

The apparatus further comprises displacing means for moving the rolls 2 toward the axis of the die 3 at a predetermined rate in response to movement of the carriage 21 in axial direction of the workpiece 1. The displacing means comprises a suitable template 5 which is tracked by the roller follower 7 of a scanning arm 6. The rate at which the rolls 2 move toward each other in response to axial movement of the die 3 from the right-hand end toward the left-hand end of the workpiece 1 (as viewed in FIG. 2) depends on the profile of the template 5, i.e., on the configuration of its surface 5a, and on the position of the template with reference to the die 3. The illustrated template 5 has a straight surface 5a so that the diameter of the blank which is obtained on treatment of the workpiece 1 decreases gradually from the right-hand end toward the left-hand end of the blank, as viewed in FIG. 2. However, it is clear that the template 5 can be replaced with a template whose surface comprises two or more axially spaced straight portions and slightly or strongly inclined intermediate portions between such axially spaced portions so that the blank then comprises axially spaced gradually tapering sections and at least one steeply or gradually sloping intermediate section which defines a more or less pronounced shoulder. Furthermore, depending on the desired conicity of the blank, on the hardness of the material of the workpiece 1, on the sturdiness of the apparatus and/or certain other factors, the blank can be obtained in a two-stage, threestage, etc., operation, i.e., the carriage 21 is then caused to advance the die 3 repeatedly in axial direction of the same workpiece; during each such pass, the rolls 2 reduce the diameters of successive increments of the workpiece to an extent which is determined by configuration and/or positioning of the template which is utilized in the respective stage of the operation.

FIG. 3 shows that the axes of shafts 8 for the rolls 2 make an acute angle and are arranged skew with re.- spect to the axis of the die 3. The rolls 2 rotate on radial bearings 9 (here shown as needle bearings) and are held against axial movement on shafts 8 by thrust bearings 10. The shafts 8 are mounted in discrete onearmed follower levers 13 each of which has a pivot pin mounted in an inner ring 12 and each of which has a suitably configurated convex follower portion 26. The scanning arm 6 is rigid with an outer ring 11 which constitutes a triple cam and has three concave internal cam faces 14 each cooperating with one of the follower portions 26. It will be readily understood that the rolls 2 move toward the axis of the die 3 when the scanning arm 6 is pivoted in-a clockwise direction, as viewed in FIG. 2. Suitable springs (not shown) are provided to bias the follower portions 26 against the respective cam faces 14 and to bias the roller follower 7 against the surface 5a of the template 5.

When the apparatus is in use, the gear or pulley 24 rotates the workpiece l which is held by the supporting members 20. The cable 22 moves the carriage 21 in axial direction of the workpiece 1 whereby the rolls 2 rotate about their axes in response to engagement with the peripheral surface of the rotating workpiece. The carriage 21 entrains the arm 6 whose roller follower 7 tracks the surface 5a of the template 5 whereby the rolls 2 advance toward the axis of the die 3 and automatically reduce the diameters of successive increments of the workpiece l in accordance with the desired schedule.

An important advantage of the improved method and apparatus is that the workpieces 1 can be converted into tapered blanks within short periods of time, in a fully automatic way or semiautomatically, with a high degree of reproducibility, and without any (or without appreciable) waste in metallic material. This is particularly important when the material is spring steel. The surface finish of blanks is exceptionally satisfactory, especially if the workpiece l is converted into a blank in two or more stages.

In accordance with a more specific feature of the present invention, the roller follower 7 is mounted on the outer end portion of the scanning arm 6 by means of a suitable swivel bearing 7a which permits the follower to wobble or swivel in order to compensate for eventual misalignment of its groove 7b with the surface 5a of the template 5. In this way, that portion of the groove 7b which receives the adjacent part of the surface 5a can move toward or away from the axis of the die 3 within limits determined by the swivel bearing 7a. The peripheral surfaces of the rolls 2 are preferably rounded (see particularly FIG. 3) to insure more satisfactory deformation of successive increments of the workpiece 1 when the carriage 21 moves to the left, as viewed in FIG. 2. Similar results can be obtained by employing conical rolls. SuCh conical or convex rolls can be used with advantage even if the axes of the shafts 8 are not inclined with reference to the axis of the die 3. The rate at which the rolls 2 move toward the axis of the die 3 while the latter travels axially of the workpiece 1 also depends on the configuration of faces 14 on the outer ring 11; such faces are preferably rounded, inclined and/or curved in such a way that they effect gradual inward movement of rolls 2 in response to angular displacement of the ring 11 at a constant speed.

It is clear that the improved apparatus is susceptible of many modifications without departing from the spirit of the present invention. For example, the die 3 can rotate with reference to the workpiece 1 which is then held against rotation or rotates at a different speed or counter to the direction of rotation of the die. Also, the die 3 can support more than three rolls and the movements of rolls 2 toward and/or away from the axis of the die 3 can be effected by mechanisms which do not necessarily employ a template. Furthermore, the apparatus can be equipped with two or more dies and with a requisite number .of supporting, driving and displacing means so that it can treat two or more workpieces at a time. If the apparatus comprises two or more dies, all of the dies can be operatively connected with a common template or each die can cooperate with a separate template.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

I claim:

1. Apparatus for converting .elongated solid rodshaped metallic workpieces of at least substantially constant diameter into blanks each of which tapers in direction from one end towards the other end thereof, comprising first supporting means arranged to hold an elongated workpiece; a die having an axis comprising at least three rolls disposed about said axis and having each an axis arranged askew at a constant angle relative to said die axis and each of said rolls having a convexly curved peripheral surface, said rolls defining between themselves a roll pass for the workpiece, and said rolls being movable toward and away from said die axis; second supporting means for holding said die in a position in which said die axis coincides with the axis of the workpiece held by said first supporting means; first drive means for rotating one of said supporting means 1 about said coinciding axes; second drive means operative to move at least one of said supporting means with reference to the other supporting means in the direction of said coinciding axes so that the convexly curved peripheral surfaces of said rolls are respectively in point engagement with successive increments of the workpiece held by said first supporting means; and displacing means for moving said rolls towards the axis of said die at a predetermined rate in response to operation of said second drive means to thereby intensify the stretch rolling action of said rolls so as to reduce'the diameter of said solid workpiece while causing the mate- I rial of said workpiece to flow in axial direction thereof.

2. Apparatus as defined in claim 1, wherein said dis- 1 placing means comprises a template having a surface of predetermined outline, follower means arranged to track said surface in response to operation of said second drive means, and means for transmitting motion 5. Apparatus as defined in claim 4, wherein said bear- I ing means include radial needle bearings for said rolls.

6. Apparatus as defined in claim 4, wherein said bearing means include thrust bearings for said rolls.

7. Apparatus as defined in claim 1, wherein said displacing means comprises substantially concentric inner and outer ring-shaped portions, follower means provided on one of said ring-shaped portions, cam means provided on the other ring-shaped portion and cooperating with said follower means, shaft means for each of said rolls, said shaft means being mounted on said follower means, and means for rotating one of said ringshaped portions with reference to the other ring-shaped portion to thereby effect relative movement between said cam means and said follower means so that the follower means moves said shaft means and the drawing members toward the axis of said die.

8. Apparatus as defined in claim .7, wherein each of said follower means is a lever which is pivotably mounted on said inner ring-shaped portion.

9. Apparatus as defined in claim 7, wherein said cam means comprises faces of a configuration which insures gradual movement of said rolls toward the axis of said die in response to rotation of said one ring-shaped por-' tion at a constant speed.

10. Apparatus as defined in claim 7, wherein said one ring-shaped portion is said outer portion and wherein the means for rotating said outer portion comprises a template and a scanning member connected with said outer portion and arranged to track said template in response to operation of said second drive means.

11. Apparatus as defined in claim 1,'wherein said first drive means is arranged to rotate the workpiece by way of said first supporting means.

12. Apparatus as defined in claim 1, wherein said second supporting means comprises a carriage and wherein said second drive means is arranged to move said carriage and said die in axial direction of the workpiece which is held in said first supporting means.

13. Apparatus-as defined in claim 1, wherein the axes of all of said rolls are inclined at an acute angle relative to said die axis.

14. Apparatus as defined in claim 1, wherein said displacing means move said rolls in substantially radial direction toward the axis of said die without changing the 

1. Apparatus for converting elongated solid rod-shaped metallic workpieces of at least substantially constant diameter into blanks each of which tapers in direction from one end towards the other end thereof, comprising first supporting means arranged to hold an elongated workpiece; a die having an axis comprising at least three rolls disposed about said axis and having each an axis arranged askew at a constant angle relative to said die axis and each of said rolls having a convexly curved peripheral surface, said rolls defining between themselves a roll pass for the workpiece, and said rolls being movable toward and away from said die axis; second supporting means for holding said die in a position in which said die axis coincides with the axis of the workpiece held by said first supporting means; first drive means for rotating one of said supporting means about said coinciding axes; second drive means operative to move at least one of said supporting means with reference to the other supporting means in the direction of said coinciding axes so that the convexly curved peripheral surfaces of said rolls are respectively In point engagement with successive increments of the workpiece held by said first supporting means; and displacing means for moving said rolls towards the axis of said die at a predetermined rate in response to operation of said second drive means to thereby intensify the stretch rolling action of said rolls so as to reduce the diameter of said solid workpiece while causing the material of said workpiece to flow in axial direction thereof.
 2. Apparatus as defined in claim 1, wherein said displacing means comprises a template having a surface of predetermined outline, follower means arranged to track said surface in response to operation of said second drive means, and means for transmitting motion from said follower means to said rolls.
 3. Apparatus as defined in claim 2, wherein said follower means comprises a roller and said displacing means further comprises swivel bearing means rotatably supporting said roller and permitting the latter to move that portion of its peripheral surface which engages the surface of said template toward and away from the axis of said die.
 4. Apparatus as defined in claim 1, wherein said die further comprises a shaft for each of said rolls and antifriction bearing means interposed between said shafts and the respective rolls.
 5. Apparatus as defined in claim 4, wherein said bearing means include radial needle bearings for said rolls.
 6. Apparatus as defined in claim 4, wherein said bearing means include thrust bearings for said rolls.
 7. Apparatus as defined in claim 1, wherein said displacing means comprises substantially concentric inner and outer ring-shaped portions, follower means provided on one of said ring-shaped portions, cam means provided on the other ring-shaped portion and cooperating with said follower means, shaft means for each of said rolls, said shaft means being mounted on said follower means, and means for rotating one of said ring-shaped portions with reference to the other ring-shaped portion to thereby effect relative movement between said cam means and said follower means so that the follower means moves said shaft means and the drawing members toward the axis of said die.
 8. Apparatus as defined in claim 7, wherein each of said follower means is a lever which is pivotably mounted on said inner ring-shaped portion.
 9. Apparatus as defined in claim 7, wherein said cam means comprises faces of a configuration which insures gradual movement of said rolls toward the axis of said die in response to rotation of said one ring-shaped portion at a constant speed.
 10. Apparatus as defined in claim 7, wherein said one ring-shaped portion is said outer portion and wherein the means for rotating said outer portion comprises a template and a scanning member connected with said outer portion and arranged to track said template in response to operation of said second drive means.
 11. Apparatus as defined in claim 1, wherein said first drive means is arranged to rotate the workpiece by way of said first supporting means.
 12. Apparatus as defined in claim 1, wherein said second supporting means comprises a carriage and wherein said second drive means is arranged to move said carriage and said die in axial direction of the workpiece which is held in said first supporting means.
 13. Apparatus as defined in claim 1, wherein the axes of all of said rolls are inclined at an acute angle relative to said die axis.
 14. Apparatus as defined in claim 1, wherein said displacing means move said rolls in substantially radial direction toward the axis of said die without changing the angle of the roll axes relative to the die axis. 